It's a competitive move; it gives Apple and their users a bragging point, causing competition an expensive countermove. Competition has to move to depth sensor cameras and more on their phones, while Apple is reducing the expense and improving the quality of theirs. The Face ID tech is immature today, but a quarter or three? The quarter after that once support issues have had a few cycles, and the Face ID team has iterated, refactored and refreshed... This is a basic tech deployment they'll only improve.
The real question to me, a person in the FR industry, will Apple iterate their camera hardware and extend the perception depth range to be competitive in the larger FR surveillance industry? The general FR industry has to recognize multiple people at a distance, and then IoT-like control other hardware, a game Apple is not touching with Face ID - yet.